1. Field of the Invention
The present invention relates to a wired circuit board, and particularly to a wired circuit board used preferably for a suspension board with circuit mounted in a hard disk drive, and a producing method thereof.
2. Description of the Related Art
A suspension board with circuit includes a metal supporting board, an insulating base layer formed thereon, and a conductive layer formed thereon and having head-side terminals to be connected to a magnetic head. On the suspension board with circuit, the magnetic head is mounted and connected to the head-side terminals, and the suspension board with circuit is mounted in a hard disk drive with the metal supporting board being supported on a load beam.
In recent years, it has been examined to connect such a suspension board with circuit to various electronic elements such as, e.g., a piezoelectric element (piezo-element) and accurately and finely adjust the position and angle of a magnetic head, and so forth. Because of its relatively low heat resistance, such an electronic element needs to be electrically connected to electronic-element-side terminals (terminals different from head-side terminals and formed with a conductive layer) at a relatively low temperature via a conductive adhesive or the like.
The low-temperature connection between the electronic element having low heat resistance and the electronic-element-side terminals via the conductive adhesive is lower in the strength of connection (adhesive force) between the conductive adhesive and the electronic-element-side terminals than high-temperature connection therebetween via a molten solder. Accordingly, it is required to sufficiently improve the connection strength.
In view of this, it has been proposed that, in the conductive layer of a wired circuit board, circular lands are provided with grooves (through grooves) formed along the circumferential directions of the lands to extend therethrough in the thickness direction thereof (see, e.g., Japanese Unexamined Patent Publication No. 2010-251619). In the wired circuit board described in Japanese Unexamined Patent Publication No. 2010-251619, a conductive paste is in contact with the upper surfaces of the lands and also filling the grooves. Since the upper surfaces of the lands and the inner side surfaces of the grooves are in contact with the conductive paste, the lands increase the contact area with the conductive paste to improve the adhesive force.